According to some embodiments, a method of operating a wireless device in a wireless system comprises allocating a first uplink sub-channel to the wireless device in a first subframe associated with the wireless device. The first uplink sub-channel comprises a portion of an uplink system bandwidth, and portions of the uplink system bandwidth outside of the first uplink sub-channel are not available for transmission in the first subframe by the wireless device. The method further comprises determining a first sounding reference signal (SRS) sub-channel. The first SRS sub-channel comprises a portion of the first uplink sub-channel in frequency domain, and the SRS sub-channel is available for transmitting SRS in the first subframe by the wireless device.